Mark IV /thiele cab question

[normandk7]

Hi guys,
I'm running a thiele cab (electrovoice) with my mark IV (electrovoice too) and i've got the best of it when i plug the cab in the 8 ohm and the combo speaker in the first 4 ohm output.
Is it ok. I know that i'm suppose to plug both my cab and my combo speaker in the 4 ohm outputs but the balance of the sound is really better when i plug it as i write in the beginning of the message.
So...is it dangerous to blow my transformer...or to do some other damage to the amplifier ????
Thanks guys

 

[MesaDCLP]

If both speakers are the same impedance then I think the ohms that the amp sees will drop lower than 4, and that's usually not safe on these amps.

If one speaker is an 8 and plugged into the 4 jack, and the other speaker is a 16 plugged into the 8 ... you are safe.

 

[trem]

Yes, you'll fry your OT sooner or later.

EDIT: OK I may be wrong about the above. Check out these threads:
http://forum.grailtone.com/viewtopic.php?t=17050
http://forum.grailtone.com/viewtopic.php?t=25889&highlight=cab%2A+different

 

[phyrexia]

boogiebabies says that's ok. i've done it and it presents no issues.

 

[normandk7]

Too bad because the thiele is on the floor and the sound is louder when i plug it in the 8 ohm jack....
But, i will take no chance and continue to plug my cab and combo speakeer in the 4 ohm jacks.
Thanks for the replys

 

[normandk7]

Sorry,
Do you mean that it's ok to do so???
No problem with my transfo???
Should i call mesa to be sure???

 

[ketiov]

General rules:

It's OK to mismatch by having a speaker with higher impedance than the amp is expecting, although it won't sound as good.


Only the 4 Ohm jacks are in parallel, as far as I understand. The 8 Ohm runs alone. So the amp is seeing 4 Ohms into 8 Ohms and 8 Ohms into 8 Ohms.

In short, it should be fine.

 

[normandk7]

I just send a email to Kris Dilbeck at mesa to be sure.
I will let you know as soon as i've got the answer

 

[trem]

Should i call mesa to be sure???

Yes, best if you call them. We're only guessing here, since your case is pretty unique. Do let us know their answer.

 

[normandk7]

Here is the answer from Mesa Boogie:

Greetings,

We do not recommend running your amp in this fashion as it is rather wearing on the tubes and more concerning would be the transformer.

Thanks

Kris

So, It's not a good idea....too bad for me!!!!!